Lee J. Silverberg

A simple, rapid and efficient protocol for the selective phosphorylation of phenols with dibenzyl phosphite☆

Abstract Phosphorylation of phenols with dibenzyl phosphite, carbon tetrachloride, N , N -diisopropylethylamine, and catalytic DMAP in acetonitrile at −10°C is rapid, mild, clean, high yielding, and selective.

2,3-Diphenyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one

The six-membered thiazine ring in the title compound, C16H15NOS, adopts a half-chair conformation, with the S atom forming the back of the chair. The base of the chair has a slight twist reflected in the r.m.s. deviation (0.0756 Å) of those five atoms from the plane defined by them. The phenyl substituents are almost perpendicular to each other [dihedral angle 87.06 (9)°]. In the crystal, molecules are linked into chains parallel to the c axis through C—H⋯O interactions.

A chemoselective, acid mediated conversion of amide acetal to oxazole: The key step in the synthesis of cardiovascular drug, ifetroban sodium

Abstract The cyclization of acetal amide was carried out with trimethylsilyl trifluoromethanesulfonate, followed by elimination using sodium methoxide to give 2,5-disubstituted oxazole, thus completing a new route to the cardivascular drug ifetroban sodium.

2-(3-Nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one.

The title compound, C20H14N2O3S, has three aromatic rings, viz. (i) a phenyl ring, (ii) a 3-nitrophenyl and (iii) a 1,3-benzothiazine fused-ring system. The dihedral angle between (i) and (ii) is 85.31 (15)°, between (ii) and (iii) is 81.33 (15)° and between (i) and (iii) is 75.73 (15)°. The six-membered 1,3-thiazine ring has an envelope conformation with the C atom in the 2-position forming the flap. In the crystal, molecules are linked by weak C—H⋯O interactions, forming a three-dimensional network.

2,3-Diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one.

In the title compound, C20H15NOS, the dihedral angle between the phenyl rings is 74.25 (6)°. The six-membered 1,3-thiazine ring has an envelope conformation with the C atom at the 2-position forming the flap. The crystal structure features weak C—H⋯O interactions, which lead to the formation of a tape motif along [110].

6,7-Diphenyl-5-thia-7-aza-spiro-[2.6]nonan-8-one.

The asymmetric unit of the title compound, C19H19NOS, contains two independent molecules (A and B), in both of which the 1,3-thiazepan-4-one ring adopts a chair-type conformation. The dihedral angles between the two phenyl rings are 65.28 (8) and 60.31 (9)° for molecules A and B, respectively. In the crystal, molecules are linked by weak C—H⋯O interactions, resulting in a three-dimensional network.

Crystal structures of 2,3-bis-(4-chloro-phen-yl)-1,3-thia-zolidin-4-one and trans-2,3-bis-(4-chloro-phen-yl)-1,3-thia-zolidin-4-one 1-oxide.

In the related title compounds, (1) and (2), the 3-thiazolidine ring pucker is twisted on the S—Cmethine bond in (1), while in (2), the ring has an envelope conformation with the S atom as the flap. In the crystal of (1), molecules are linked by C—H⋯O hydrogen bonds forming chains along [100], while in the crystal of (2), molecules are linked by C—H⋯O and C—H⋯Cl hydrogen bonds forming slabs parallel to (001).

Crystal structures of 2-(4-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one and 2-(2-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one.

In the crystal structures of the racemic para and ortho isomers of 2-(4-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one, the six-membered thiazine ring of the benzothiazone parent molecule displays a screw-boat conformation and a near-screw-boat conformation, respectively. In the crystals of both isomers, weak C—H⋯O hydrogen-bonding interactions give rise to one-dimensional structures.

2,3-Diphenyl-1,3-thia-zolidin-4-one.

The title compound, C15H13NOS, is a chiral molecule crystallized as a racemate, with two molecules in the asymmetric unit. In each of the molecules, the five-membered thiazine ring has an envelope conformation, with the S atom forming the flap. In one molecule, the angle between the two phenyl-ring planes is 82.77 (7)°, while in the other it is 89.12 (6)°. In the crystal, molecules are linked into chains along the b-axis direction by C—H⋯O hydrogen bonds.

Spontaneous resolution and crystal structure of (2S)-2-(3-nitro­phen­yl)-3-phenyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one; crystal structure of rac-2-(4-nitro­phen­yl)-3-phenyl-2,3,5,6-tetra­hydro-4H-1,3-thia­zin-4-one

One of the racemic title isomers crystallized in a centrosymmetric space group and the other spontaneously resolved into enantiomers.